A card reader/writer used for ATM machines (hereinafter denoted as a card reader), as illustrated in FIG. 3, is equipped with a card detecting switch 6, which is arranged near a card insertion slot to detect the insertion of a card 3, and a card position detector (not illustrated), which is arranged inside the card reader to detect the position of the card. The card detecting switch 6 is turned on as pressed by the inserted card 3 in the lateral direction; it is turned off as the card 3 is detached from the switch. The card position detector is a photo sensor composed of a photo-emitting device and a photo-receiving device, and emits a light beam to pass across a card running path 9 so that the presence of the card 3 can be recognized depending on the detection of the light. In addition to the on/off mechanism of the card detecting switch 6 and the card position detector, the number of steps of a stepping motor, which is output when the card 3 is transported, is used to calculate the length of the card 3. Based on the calculation value, it is determined whether the length of the card is proper.
Note that code 5 in FIG. 3 is given to a prehead which recognizes the insertion of the card 3 by searching magnetic information recorded on a magnetic strip 2 of the card 3. A conventional card reader only detects the insertion of a card using the prehead 5.
In a method in which the card detecting switch 6 is used to recognize the presence of the card 3 with the lateral sides and to detect the length of the card 3, the card position detector can obtain the information on the card in the longitudinal direction and detect the presence of the card 3 in the lateral direction. Thus, this method is effective in determining if the card has a proper length in both longitudinal and lateral directions.
In recent years, cards have made in different shapes for the design appeal. In other words, cards are not always in a standard rectangular shape (see FIG. 5). Accordingly, a card reader needs to determine if the card inserted is in a standard shape or in a special non-standard shape; when the card is in a special non-standard shape, the card reader needs to warn that the writing on the card may be degraded or cannot be guaranteed. (See Laid-open Patent Application H8-96093).
However, in the above-mentioned card reader, the card detecting switch is used to detect the presence of the card only when it is pressed by the card toward the lateral side. Therefore, as illustrated in FIG. 5, a card having a short side that is pressed toward the card detecting switch, i.e., a card in a non-standard shape cannot be detected, degrading the accuracy of judgment on the appropriateness of the card length.
Even when a card is identified as non-standard shape, the card reader still cannot determine if the card was originally in a special, non-standard shape that the card reader can process or if the card may have been broken and resulted in an abnormal shape that the card reader cannot process. In other words, although a conventional card reader can determine the shape of the card to some extent, it cannot differentiate the variety in shapes, such as between a standard shape and a special non-standard shape. For example, the card shown in FIG. 5 shows an example where the magnetic information recorded on the magnetic strip can be read although the writing performance will be degraded. Thus, it is possible for a card reader to selectively process the reading of the magnetic information in this case.
Therefore, it is desirable to provide a card reader that can not only identify a non-standard card shape, but also can differentiate a special non-standard shape from an abnormal shape.